Cogeco Internet Not Working — Modem & Router Fixes

Applies to: Cogeco internet (Ontario, Quebec)

If your address used to be served by DERYtelecom in the Saguenay region of Quebec, that brand was fully absorbed into Cogeco in 2023 — same underlying service and troubleshooting steps apply.

1. Check the physical connections first

1. Confirm the coaxial cable is screwed on tightly at both the wall outlet and the modem — not just resting in place.
2. Confirm all cables are properly connected between your equipment and their power outlets.

2. Factory reset the modem

1. Locate the small RESET pinhole on the back of the modem.
2. Hold it with a pin or similar sharp object for a full 30 seconds.
3. Allow a full 10 minutes for the equipment to completely reboot before testing.

3. Modem has correct lights, but the router shows offline

1. Check the Ethernet cable between the modem and router is fully seated — you should feel or hear a click when both ends are pushed in completely.
2. Reset the modem again specifically, even if it looked fine, to force it to re-establish any connection that may have quietly dropped.
3. Power everything down, then bring it back up in order: modem first, wait for all lights to go solid, then the router, then your other devices.

4. Isolate whether it's the modem or your own router

Connect a computer directly to the Cogeco modem with an Ethernet cable, bypassing your router entirely. If that works fine, the modem and your service are both working — the problem is specific to your router.

5. Using your own router: watch for double-NAT

If your own router is set up as a router (rather than in bridge/access-point mode) while Cogeco's modem is also handling its own NAT and DHCP, you can end up with two layers of NAT running at once — often causing intermittent slowdowns or connections that work briefly then degrade every 10-15 minutes.

1. Check whether devices connected to your own router get a private IP address (starting with 192.168.x.x) even while online — if so, the modem is likely already providing its own NAT.
2. If that's the case, turn off DHCP on your own router and connect its WAN port to one of the modem's standard LAN ports instead of its WAN port, so the modem's DHCP handles addressing for everything.

6. Repeated slowdowns every 10-15 minutes

If the connection works fine briefly after a reset but degrades on a consistent short cycle, this is a classic symptom of the double-NAT issue above rather than a line or account problem — worth ruling out before contacting support.

FAQ